<template>
  <div class="child">
    <h3>我是child组件</h3>
    {{sum}}
  </div>
</template>
<script>
import{ref} from "vue";
export default {
  name: 'Child',
  async setup(){
    let sum=ref(0)
let p= new Promise((resolve)=>{
  setTimeout(()=>{
    resolve({sum})
  },3000)
})
    return await p
  }
}
</script>

<style>
.child{
  background-color: skyblue;
  padding: 10px;
}
</style>
